The hydraulic system

The hydraulic system is a closed circuit (loop), see Fig. A.1 and A.6. Water is pumped from a stainless steel water reservoir (or tank) to the target, and then back to the tank through stainless steel tubes. In order to produce a stable film, a gear pump, magnetically coupled to a dc motor, is used.

A tachometer which is on the pump axis measures the pump speed (turn/min), and a flowmeter, which is placed before the entrance of the scattering chamber, measures the flow rate. The set voltage is also read, although it is redundant. These parameters can be used to monitor the target thickness stability.

Figure A.6: The Hydraulic system: a schematic view.